/*
* Copyright (c) 2008 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
** This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
** Please obtain a copy of the License at
*http://www.opensource.apple.com/apsl/ and read it before using this file.
** The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
** @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <sys/appleapiopts.h>
#include <machine/cpu_capabilities.h>
#include <machine/commpage.h>
#include <i386/asm.h>
#include <assym.s>
/*
* These commpage routines provide fast access to the logical cpu number
* of the calling processor assuming no pre-emption occurs. This number
* is encoded in the bottom 12-bits of the limit field of the IDTR (the
* Interrupt Descriptor Table Register). The SIDT instruction is used in
* userspace to read this register and thus to gain access to the cpu number.
* The IDTR is loaded by the kernel for each processor at startup - see
* osfmk/i386/mp_desc.c.
*/
/* return logical cpu number in %eax */
COMMPAGE_FUNCTION_START(cpu_number, 32, 4)
push %ebp
mov %esp,%ebp
sub $8, %esp // space to read IDTR
sidt (%esp) // store limit:base on stack
movw (%esp), %ax // get limit
and $0xfff, %eax // mask off lower 12 bits to return
mov %ebp,%esp
pop %ebp
ret
COMMPAGE_DESCRIPTOR(cpu_number,_COMM_PAGE_CPU_NUMBER,0,0)
/* The 64-bit version.
*/
COMMPAGE_FUNCTION_START(cpu_number_64, 64, 4)
push %rbp
mov %rsp,%rbp
sub $16,%rsp // space to read IDTR
sidt (%rsp) // store limit:base on stack
movw (%rsp), %rax // get limit
and $0xfff, %rax // mask off lower 12 bits to return
mov %rbp,%rsp
pop %rbp
ret
COMMPAGE_DESCRIPTOR(cpu_number_64,_COMM_PAGE_CPU_NUMBER,0,0)